Pulley with belt-wiping surfaces

ABSTRACT

A pulley plate, a pulley and a belt drive system are disclosed. Each include a pulley plate or a pulley having an inner surface adapted to be driven about an axis of rotation and having a perimeter. The inner surface additionally includes a plurality of belt-wiping grooves at least partially between the axis and the perimeter. The plurality of belt-wiping grooves are located or patterned in the inner surface so as to contact the belt in different locations to reduce wear on the wall of the belt. In one embodiment, the plurality of belt-wiping grooves are centered about the axis and are unequally circumferentially spaced from one another. In another embodiment, the plurality of belt-wiping grooves are centered about a center offset from the axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S applicationSer. No. 09/085,809 filed on May 27, 1998 now U.S. Pat. No. 6,165,093 byMaury V. Salz and John D. Gates, the full disclosure of which is herebyincorporated by reference. Priority is claimed from U.S. applicationSer. No. 09/085,809 under 35 U.S.C. §120.

FIELD OF THE INVENTION

The present invention relates to a variable speed pulley system fortransmitting power from one location to another. In particular, thepresent invention relates to a pulley plate for use with an opposingpulley plate having a belt disposed therebetween. The pulley plateincludes a belt-wiping surface or feature obliquely extending from thepulley plate's inner surface and located so as to engage the belt and toremove debris.

BACKGROUND OF THE INVENTION

Variable speed pulley systems are used for transmitting power from onelocation to another in applications requiring an adjustable drive ratiobetween a drive shaft and a driven shaft. The pulley systems aretypically powered by an engine or other drive mechanism. Asconventionally known, variable speed pulley systems may be used to drivea multitude of secondary mechanisms for performing a variety ofdifferent functions.

Variable speed pulley systems usually include a drive pulley, a drivenpulley, and a belt. The drive pulley generally comprises two pulleyplates, one of which is anchored and the other of which is movable withrespect to the anchored pulley plate. The belt extends from betweenthese two plates on one end to some distal pivot, which may be anothersheave comprising two spaced apart pulley plates and a torque sensingunit for accommodating fluctuating loads. The torque sensing unit, asdescribed in U.S. Pat. No. 4,173,155 issued to Togami et al, reacts to aquick change in the load applied by the belt (for example, in responseto a large mat or quantity of material entering a threshing mechanism).

Each pulley plate of the drive and driven pulleys has a face thatencompasses a pulley contact surface. The pulley contact surfaces of twopulley plates of either the drive or driven pulley face one another. Thepulley contact surfaces are generally angled so that as the distancebetween the pulley plates is reduced, the belt is forced into contactwith the faces of the plates at a greater spacing from the center of thefaces. Conversely, as the plates are moved apart, the belt is allowed tocontact the faces of the plates at a smaller spacing from the center.

Many of the machines employing a pulley system as a component, such asagricultural and construction equipment, are subject to large amounts ofdirt, dust and chaff which fills the air and becomes deposited upon thepulley plates and the belt. This problem is of special concern inharvesting machines such as combines where the harvesting machine itselfgenerates a large volume of chaff during the harvest of crops. The dirt,dust and chaff which become deposited upon the pulley plates reduce thecoefficient of friction between the pulley plates and the belt causingthe belt to slip and heat up. As a result, the dust, dirt and chaffdeposited upon the pulley plates and the belt reduce belt life andreduce power transmission efficiency. Variable speed pulleys and pulleysused in conjunction with torque sensing devices have an additionalproblem in that the engagement between the pulley plates and the beltoccurs over a small surface area. Consequently, even in a cleanenvironment, it is desirable to increase the friction between the platesand the belt in order to achieve greater power through-put values.

Thus, there is a continuing need for a device that removes debris fromthe belt and increases the friction between the pulley plate and belt ofa pulley system without requiring dismantling of the pulley system.

SUMMARY OF THE INVENTION

According to one exemplary embodiment, a pulley for use with a beltincludes a first surface, a second surface facing the first surface, anda first plurality of belt-wiping grooves in the first surface. The firstand second surfaces are adapted to rotate about an axis extendingthrough the first and second surfaces. Each of the first and secondsurfaces includes an outer perimeter. The first plurality of belt-wipinggrooves in the first surface extend at least partially between the axisand the perimeter and are unequally circumferentially spaced from oneanother.

According to another exemplary embodiment, a pulley for use with a beltincludes a first surface, a second surface and a plurality ofbelt-wiping grooves in the first surface. The first and second surfacesare spaced from one another to receive the belt and are adapted torotate about an axis extending through the first and second surfaces.Each of the first and second surfaces includes an outer perimeter. Theplurality of belt-wiping grooves in the first surface extend at leastpartially between the axis and the perimeter and are centered about acenter offset from the axis.

According to another exemplary embodiment, a pulley plate for use withan opposing pulley plate so as to receive a belt therebetween includesan inner surface adapted to face the opposing pulley plate and aplurality of belt-wiping grooves in the inner surface. The inner surfacehas an outer perimeter and a first center about which the pulley plateis adapted to rotate. The plurality of belt-wiping grooves in the innersurface extend at least partially between the first center and theperimeter. The plurality of belt-wiping grooves are unequallycircumferentially spaced from one another.

According to another embodiment, a belt drive system includes a drivepulley, a driven pulley, and a belt. The drive pulley includes a firstinner surface and a second inner surface facing the first inner surface.The first and second inner surfaces are spaced to form a first recessand rotate about a first axis extending through the first and secondinner surfaces. The driven pulley includes a third inner surface and afourth inner surface facing the third inner surface. The third andfourth inner surfaces are spaced to form a second recess and rotateabout a second axis extending through the third and fourth innersurfaces. The belt is received within the first and second recesses toconnect the drive pulley to the driven pulley. At least one of theopposing inner surfaces includes a perimeter and a plurality ofbelt-wiping grooves unequally circumferentially spaced from one another.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view illustrating a harvestingmachine including a belt drive system of the present invention.

FIG. 2 is a sectional view of the pulley of the belt drive system ofFIG. 1.

FIG. 3 is an elevational view of the first pulley plate of the pulley ofFIG. 2 taken along line III—III.

FIG. 4 is an enlarged fragmentary sectional view of the pulley of FIG. 2taken along line IV—IV.

FIG. 5 is an elevational view of a second opposing pulley plate of thepulley of FIG. 2 further illustrating two alternative grooveorientations in phantom.

FIG. 6 is an elevational view of a prior art pulley plate adjacent abelt shown in phantom.

FIG. 7 is an elevational view of a first alternative embodiment of thepulley plate of FIG. 5.

FIG. 8 is an elevational view of a second alternative embodiment of thepulley plate of FIG. 5.

FIG. 9 is an elevational view of a third alternative embodiment of thepulley plate of FIG. 5.

FIG. 10 is an elevational view of a fourth alternative embodiment of thepulley plate of FIG. 5.

FIG. 11 is an elevational view of a fifth alternative embodiment of thepulley plate of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a fragmentary sectional view of a harvesting machine 10including belt drive system 60. Harvesting machine 10 preferablycomprises a conventionally known combine including header 12 andthreshing mechanism 16. Header 12 is adapted to harvest crops and feedthe crops via feeder 14 into threshing mechanism 16. Threshing mechanism16 separates the grain or seeds from the remaining straw and chaff.Threshing mechanism 16 is driven by belt drive system 60. Belt drivesystem 60 includes drive pulley 62, driven pulley 61 and belt 63extending therebetween.

Drive pulley 62 is preferably a variable speed pulley comprising twospaced apart pulley plates 30, 31 and belt 63 disposed therebetween.Preferably pulley plate 30 is anchored and pulley plate 31 is axiallydisplaceable with respect to pulley plate 30 (by a conventionalmechanism not shown). In one embodiment, belt-wiping surfaces (shown,for example, in FIGS. 2-5 and described in relation to pulley plates 70,80) are provided on the inner surfaces of both pulley plates 30, 31.However, belt-wiping surfaces may be provided only on the inner surfaceof one of the pulley plates. Drive pulley 62 is connected via a driveshaft (not shown) to a motor or engine (not shown). The motor rotatesthe drive shaft, which in turn rotates drive pulley 62. As drive pulley62 rotates, it frictionally engages belt 63 such that belt 63 movesalong its length.

Driven pulley 61 generally comprises anchored pulley plate 70 andaxially displaceable pulley plate 80. Pulley plates 70, 80 includeopposing inner surfaces 72, 82 spaced so as to receive belt 63 (shownmore clearly in FIGS. 2 and 3). Inner surfaces 72, 82 frictionallyengage belt 63 such that, as belt 63 moves as described above, pulleyplates 70, 80 rotate. Pulley plates 70, 80 are drivingly mounted tothreshing mechanism 16 rotates. Thus, belt 63 transmits the rotationalforce applied to drive pulley 62 by a motor to each of pulley plates 70,80.

Pulley plates 70, 80 preferably include belt-wiping surfaces 701, 801(shown in FIGS. 2-5) extending from inner surfaces 72, 82.Alternatively, only one pulley plate includes a belt-wiping surface.Belt-wiping surfaces 701, 801 scrape edges 64 of belt 63 to improve thefrictional engagement between belt 63 and pulley plates 70, 80.

FIG. 2 is a sectional view illustrating driven pulley 61 of belt drivesystem 60 in greater detail. Driven pulley 61 comprises torque sensingunit 120, driven shaft 92, belt receiving space 40, belt 63, anchoredpulley plate assembly 170, axially displaceable pulley plate assembly180 and belt-wiping surfaces 701, 801.

Torque sensing unit 120 will be discussed briefly, but is addressed inmore detail in U.S. Pat. No. 4,173,155 issued to Togami et al, the fulldisclosure of which is hereby incorporated by reference. Torque sensingunit 120 comprises cam hub 100, biasing spring 150, cam follower hub130, cam followers 131 and cam sleeve 140. Torque sensing unit 120generally has two functions: to bias pulley plate 80 toward anchoredpulley plate 70, and to transmit the rotation of pulley plate 80 todriven shaft 92. Torque sensing unit 120 generally applies a constantbiasing force through spring 150 and a variable biasing force, as afunction of the resistance applied by belt 63, through cam follower hub130 and followers 131 to pulley plate 80. Thus, unit 120 promotestension against belt 63 and frictional engagement between plates 70, 80and belt 63. In addition, torque sensing unit 120 transmits the rotationof pulley plate 80 to driven shaft 92 through cam sleeve 140 and hub100.

Cam hub 100 is generally tubular and receives distal end 94 of drivenshaft 92. Cam hub 100 is non-rotatably connected to cam sleeve 140. Camhub 100 is drivingly mounted to driven shaft engaging hub 75 of pulleyplate assembly 170 with a spline connection (not shown). Cam hub 100compresses biasing spring 150 against pulley plate 80. Cam hub 100 alsoworks in cooperation with follower hub 130, followers 131, and sleeve140 to transmit the rotation of pulley plate 80 to driven shaft 92 aswill be described hereinafter. Specifically, through the connection tocam sleeve 140, cam hub 100 receives rotation, and through the splineconnection to driven shaft engaging hub 75, transmits rotation to pulleyplate assembly 170.

Biasing spring 150 is a spring disposed between pulley plate 80 and camhub 100 and around driven shaft 92. Spring 150 is compressed between hub100 and pulley plate 80 so that spring 150 applies a constant biasingforce on pulley plate 80, forcing pulley plate 80 toward pulley plate70.

Cam follower hub 130 is generally tubular and includes proximal end 132and distal end 133. Follower hub 130 is secured to pulley plate 80 atproximal end 132 and receives cam followers 131 at distal end 133.Follower hub 130 initially responds to an increase in the load appliedto pulley 61 through belt 63 by moving away from pulley plate 70. Torquesensing cam followers 131, in a conventionally known manner as describedin Togami, U.S. Pat. No. 4,173,155, push follower hub 130 back towardpulley plate 70 thereby increasing the biasing force against pulleyplate 80. The increase in the applied biasing force pushes pulley plate80 toward pulley plate 70 such that belt 63 engages pulley 61 adjacentedges 78, 86 of pulley plates 70, 80. Conversely, as the load decreases,follower hub 130 relaxes the biasing force applied against pulley plate80.

Torque sensing cam followers 131 are conventionally known bearingsextending from follower hub 130 radially inwardly to recesses (notshown) in cam sleeve 140. Followers 131 engage the recesses as followerhub 130 rotates, thus rotating sleeve 140. In addition, as follower hub130 moves axially, followers 131 move axially within the recesses. Thefunctioning of followers 131 is described in U.S. Pat. No. 4,173,155 andis not shown here in detail.

Cam sleeve 140 is generally tubular with recesses at end 141 forreceiving followers 131. Sleeve 140 is connected to hub 100 opposite end141. Through this connection sleeve 140 transmits rotation (applied tosleeve 140 via followers 131 as described previously) to hub 100. Thus,rotation of pulley plate 80 is transmitted to driven shaft 92 by torquesensing unit 120 in the following manner: Pulley plate 80 rotates andtransmits the rotation to follower hub 130 via the connection atproximal end 132; follower hub 130 transmits rotation to sleeve 140through the interference between the recesses in sleeve 140 andfollowers 131; sleeve 140 is connected to hub 100 and thereforetransmits rotation to hub 100; hub 100 transmits rotation to pulleyplate assembly 170 through the spline connection (described above);finally, pulley plate assembly 170 transmits rotation to driven shaft 92through the spline connection between pulley plate assembly 170 anddriven shaft 92 (described below).

Driven shaft 92 comprises proximal end 91, distal end 94, and attachingmeans 95. Driven shaft 92 is conventionally known for drivinglyattaching driven pulley 61 to threshing mechanism 16 (or any otherdevice to be driven). Driven shaft 92 is received within driven shaftreceiving hub 75 of pulley plate assembly 170. Distal end 94 is texturedso as to effect a spline connection between driven shaft 92 and pulleyplate assembly 170 such that rotation of pulley plate 70 is transmittedto driven shaft 92. Attaching means 95 includes bolt 96 and washer 97fitting over distal end 94. The spline connection and attaching means 95work in conjunction to prevent axial movement of pulley plate assembly170 with respect to driven shaft 92.

Belt receiving space 40 is defined by inner surfaces 72, 82 of pulleyplates 70, 80. Belt receiving space is preferably narrower at proximalend 41 and wider at distal end 42 because inner surfaces 72, 82 areangled (described hereinafter). The width of belt receiving space vanesas pulley plate 80 moves with respect to pulley plate 70. Belt receivingspace 40 reaches a minimum width when pulley plate 80 is minimallydisplaced from pulley plate 70. Conversely, belt receiving space 40reaches a maximum width when pulley plate 80 is maximally displaced frompulley plate 70. When an increased load is applied to driven shaft 92and slippage of belt 63 results, the width of belt receiving space 40 isdecreased (by forcing pulley plate 80 toward pulley plate 70 as has beendescribed in relation to torque sensing unit 120) and the effectivediameter of pulley 61 is increased to overcome the increase in load andto prevent belt slippage.

Belt 63 is disposed such that it extends from drive pulley 62 to drivenpulley 61. At driven pulley 61, belt 63 is disposed between anchoredpulley plate 70 and axially displaceable pulley plate 80 in beltreceiving space 40. As pulley 62 is rotated by an engine or motor (notshown), pulley 62 frictionally engages belt 63 such that belt 63 movesalong its length, traveling on a path defined by the circumference ofbelt 63. As belt 63 moves, belt edges 64 engage pulley plates 70, 80 oninner surfaces 72, 82. The friction between belt edges 64 and innersurfaces 72, 82 transmits the rotational force applied to drive pulley62 to driven pulley 61 such that pulley plates 70, 80 rotate about axisX—X. Pulley plates 70, 80 transmit this rotational force to driven shaft92, as described above.

Pulley plate assembly 170 includes driven shaft engaging hub 75 andpulley plate 70. Pulley plate assembly 170 engages belt 63 with pulleyplate 70 and transmits the received rotation from belt 63 to drivenshaft 92 through hub 75.

Driven shaft engaging hub 75 extends from inner surface 72 therebydefining aperture 79, and receives driven shaft 92 therein. Inner wall76 of hub 75 is textured at distal end 77 to act with textured distalend 94 of driven shaft 92. The resulting spline connection directlytransmits rotation of pulley plate 70 to driven shaft 92. Alternatively,any means of drivingly fastening anchored pulley plate 70 to drivenshaft 92 may be substituted.

Pulley plate 70 is generally disc shaped and includes outer edge 78,inner surface 72, outer surface 73 and groove 71. Inner surface 72extends opposite outer surface 73 and provides a face for engaging belt63. Inner surface 72 is preferably angled for varying the width of beltreceiving space 40 to respond to the varying applied load (describedpreviously).

Groove 71 is located in inner surface 72 and preferably extendssubstantially from aperture 79 to outer edge 78. Groove 71 definesbelt-wiping surface 701 from inner surface 72 toward outer surface 73.

Similar to anchored pulley plate assembly 170, axially displaceablepulley plate assembly 180 includes pulley plate 80 connected to tubularhub 85. Pulley plate assembly 180 engages belt 63 with pulley plate 80,and tubular hub 85 slidably engages driven shaft engaging hub 75 ofpulley plate assembly 170. Tubular hub 85 extends from outer surface 83,thereby defining aperture 89, and is concentrically mounted about hub 75of pulley plate assembly 170.

Pulley plate 80 is generally disc shaped and includes outer edge 88,inner surface 82, outer surface 83 and groove 81. Inner surface 82extends opposite outer surface 83 and provides a face for engaging belt63. Inner surface 82 is preferably angled such that the width of beltreceiving space 40 can be varied (as described previously). Innersurface 82 preferably faces inner surface 72 to define belt receivingspace 40 therebetween.

Groove 81 is located in inner surface 82 and preferably extendssubstantially from aperture 89 to outer edge 88. Groove 81 definesbelt-wiping surface 801 from inner surface 82 toward outer surface 83.

FIGS. 2-5 illustrate belt-wiping surfaces 701, 801 of pulley plates 70,80. Belt-wiping surfaces 701, 801, extend non-parallel from innersurfaces 72, 82 of pulley plates 70, 80. In the preferred embodimentshown in FIG. 2, belt-wiping surfaces 701, 801 extend from innersurfaces 72, 82 towards outer surfaces 73, 83 forming grooves 71, 81 ininner surface 72, 82 (shown in detail in FIG. 4). In the optimalembodiment, belt-wiping surfaces 701, 801 extend perpendicularly frominner surfaces 72, 82 toward outer surfaces 73, 83 respectively.Belt-wiping surfaces 701, 801 may extend at any angle from innersurfaces 72, 82 toward the outer surfaces 73, 83 that permitsbelt-wiping surfaces 701, 801 to engage and wipe belt edges 64.Belt-wiping surfaces 701, 801 wipe edges 64 of belt 63 to removeimpurities, thereby increasing the friction between belt 63 and pulleyplates 70, 80 respectively. Increased friction translates into increasedthrough-put values for power transmission. As belt 63 moves, edges 64engage belt-wiping surfaces 701, 801 of grooves 71, 81 to wipe beltedges 64. Belt edges 64 are effectively scraped by their engagement withbelt-wiping surfaces 701, 801.

As shown by FIG. 4, the basic components of groove 81 (althoughbelt-wiping surface 801 is shown, belt-wiping surface 701 is similar)include belt-wiping surfaces 801, recess 802, and bottom 803. Althoughthe cross-section of groove 81 is shown as U-shaped, various othershapes may be used to form belt-wiping surfaces 801 such as V-shaped orsquare. The depth of groove 81 is shown in FIG. 4 as approximately 2.0mm, however the depth of the groove may be varied. Alternatively,belt-wiping surfaces 701, 801 can extend non-parallel from inner surface72, 82 away from outer surface 73, 83.

FIG. 3 is an elevational view taken along line 3—3 illustrating plate 70in greater detail. As best shown by FIG. 3, belt-wiping surfaces 701 arethe edges of a continuous generally annular groove 71, eccentric withrespect to the center of pulley plate 70. A portion of wiping surfaces701 extend substantially the entire length of the radius of pulley plate70 50 that the wiping action occurs over the full range of loads pulley61. Therefore, whether the belt engages plate 70 close to aperture 79 orclose to circumferential edge 78, belt 63 still engages belt-wipingsurfaces 701. Wiping surfaces 701 could, in the alternative, be theedges to a substantially elliptical groove. Furthermore, wiping surfaces701 could be configured as the edges of a radially extending groove. Inaddition, pulley plate 70 can include a plurality of belt-wipingsurfaces 701. This is not meant to be an exhaustive list of patterns forbelt-wiping surface 701. Any surface arranged such that belt 63 engagesthe surface over a substantial portion of the range of loads and speedsof the torque sensing pulley is acceptable. It is desirable to providethe wiping action over substantially the full range of possible loadsand speeds so that belt 63 is being constantly wiped.

FIG. 5 is an elevational view of a second opposing pulley plate 70 ofvariable speed pulley 61. FIG. 5 depicts pulley plate 70 and includes,in phantom, alternative grooves 810, 820 defining alternative beltwiping surfaces 811, 821. Grooves 810, 820 and surfaces 811, 821 areidentical to groove 81 and surface 801 except that grooves 810, 820 andsurfaces 811, 821 eccentrically extend about axis X—X. As will beappreciated, grooves 810, 820 and surfaces 811, 821 might have variousother orientations on plate 80.

FIG. 6 illustrates a prior art pulley plate 970 while FIG. 7 illustratespulley plate 1070, an alternative embodiment of the previously describedpulley plates 70, 80. As shown by FIG. 6, pulley plate 970 has an innersurface 972 having an outer perimeter 974 and adapted to rotate about arotational axis 976. Inner surface 972 includes a plurality ofequidistantly spaced grooves 976 extending from perimeter 974 towardsrotational axis 976. Grooves 976 form a pattern about rotational axis976 and are equally circumferentially spaced from one another by anangle θ. As shown in FIG. 6, point A on belt 980 is in contact withgroove 976 h. Absent any slip, pulley A on belt 980 will travel 2 πrduring every revolution of pulley plate 970, where r is the radius ofplate 970. Since each of grooves 976 a-976 h are equidistantly spacedfrom one another about rotational axis 976, point A on belt 980 contactsa similar point on a groove 976 a-976 h during every revolution ofpulley plate 970 by Y(2 πr)/N where Y is a whole number and where Nequals the number of grooves 976 in plate 970. In the exemplary ofpulley plate 970, N equals 8. Because existing pulley plates, such asplate 970, have grooves formed in patterns that are symmetrical aboutthe pulley centerline or rotational axis 976, the grooves are morelikely by a factor of N to contact the belt 980 in the same location.The more often a groove contacts belt 980 in the same location, thehigher the wear on the wall of belt 980. Increased wear lowers the powercapacity and the life of the belt.

FIG. 7 is a side elevational view of pulley plate 1070. Pulley plate1070 has an inner surface 1072 which faces an inner surface of anopposing pulley plate (such as shown by FIG. 2). Inner surface 1072 hasa perimeter 1074 and is adapted to be rotatably driven about rotationalaxis 1076. Inner surface 1072 further includes a plurality ofbelt-wiping grooves 1076 a-1076 h. Belt-wiping grooves 1076 a-1076 hextend in inner surface 1072 between rotational axis 1076 and perimeter1074. In the exemplary embodiment, grooves 1076 a-1076 h extend fromperimeter 1074 inwardly towards rotational axis 1076. However, unlikegrooves 976 a-976 h, grooves 1076 a-1076 h are formed in a patternhaving a center 1080 which is offset from rotational axis 1076 by adistance X. In the exemplary embodiment, each of grooves 1076 a-1076 hextend along a centerline or axis that passes through center 1080.Although grooves 1076 a-1076 h are equally circumferentially spacedrelative to one another by an angle θ′, because grooves 1076 a-1076 hare centered about center 1080 which is offset from rotational axis1076, point A on belt 980 does not contact a groove 1076 at the samepoint during rotation of the pulley plate 1070. As a result, grooves1076 a-1076 h wipe edges of belt 980 to remove impurities and increasefriction between belt 980 and pulley plate 1070 without repeatedlycontacting belt 980 at the same location or point. Consequently, pulleyplate 1070 reduces the wear on the walls of belt 980 to increase thepower capacity and life of belt 980. In short, pulley plate 1070provides a maximum cleaning effect on belt 980 while minimizing the wearcaused on belt 980.

In the exemplary embodiment, each groove 1076 extends into inner surface1072 by a distance of approximately 2.0 millimeters. However, as will beappreciated, the depth may be varied. In the exemplary embodiment, eachgroove 1076 forms rounded edges or corners adjacent inner surface 1072.Alternatively, such grooves may have shoulders, or edges near the top ofthe grooves which are sharp.

In the exemplary embodiment, pulley plate 1070 is configured for use inbelt drive system 60, wherein the pulley plate opposing pulley plate1070 has an inner surface including the plurality of belt-wipingsurfaces substantially identical to those illustrated in FIG. 7 withrespect to pulley plate 1070. Alternatively, pulley plate 1070 may beutilized in a belt drive system in which only one of the plates includesbelt-wiping grooves 1076. Moreover, in lieu of pulley plate 1070 beingutilized in a variable speed pulley, pulley plate 1070 may alternativelybe utilized in other pulley arrangements where the pulley plates are notmovable relative to one another or where opposing pulley plates arepermanently fixed to one another at a predetermined spaced apartrelationship or are integrally formed with one another as part of asingle unitary pulley.

FIGS. 8-11 illustrate additional alternative embodiments of pulleyplates 70 and 80 which also provide maximum cleaning effect upon belt980 while reducing the wear caused on the belt 980 as compared to priorart of the pulley plates such as that shown in FIG. 6. FIG. 8 is a sideelevational view of pulley plate 1170. Pulley plate 1170 is similar topulley plate 1070 except that pulley plate 1170 includes a plurality ofbelt-wiping grooves 1176 a-1176 h in lieu of grooves 1076 a-1076 h.Grooves 1176 a-1176 h are substantially identical to grooves 1076 a-1076h except that grooves 1176 a-1176 h arcuately extend between perimeter1074 and rotational axis 1076. Like grooves 1076 a-1076 h, grooves 1176a-1176 h are centered about or form a pattern centered about an axis1080 offset from the rotational axis 1076. In particular, each of thegrooves 1176 a-1176 h extends along a spiral which, if extended, wouldpass through center 1080.

FIG. 9 is a side elevational view of pulley plate 1270, an alternativeembodiment of pulley plate 1170. Pulley plate 1270 is similar to pulleyplate 1170 except that pulley plate 1270 includes a plurality ofbelt-wiping grooves 1276 a-1276 f in lieu of grooves 1176 a-1176 h.Grooves 1276 a-1276 f are substantially identical to grooves 1176 a-1176h except that grooves 1276 a-1276 f are unequally circumferentiallyspaced from one another by different angles θ. Like grooves 1176 a-1176h, grooves 1276 a-1276 f are situated so as to provide maximum cleaningeffect upon belt 980 while minimizing wear on belt 980.

FIG. 10 is a side elevational view of pulley plate 1370, an alternativeembodiment of pulley plate 1170. Pulley plate 1370 is similar to pulleyplate 1170 except that pulley plate 1370 includes belt-wiping grooves1376 a-1376 f in lieu of grooves 1076 a-1076 h. Grooves 1376 a 1376 fare substantially identical to grooves 1076 a-1076 h except that grooves1376 a-1376 f are unequally circumferentially spaced from one anotherabout center 1080 which is offset from rotational axis 1076. Likegrooves 1076 a-1076 h, grooves 1376 a-1376 f provide maximum cleaningeffect upon belt 980 while minimizing any wear on belt 980.

FIG. 11 is a side elevational view of pulley plate 1470, an alternativeof pulley plate 1370. Pulley plate 1470 is similar to pulley plate 1370except that pulley plate 1470 includes a plurality of belt-wipinggrooves 1476 a-1476 f in lieu of grooves 1376 a-1376 f. Grooves 1476a-1476 f are similar to grooves 1376 a-1376 f except that grooves 1476a-1476 f are centered about rotational axis 1076 instead of center 1080.However, unlike pulley plate 970, grooves 1476 a-1476 f are unequallycircumferentially spaced from one another about rotational axis 1076. Inother words, grooves 1476 a-1476 f are angularly offset relative to oneanother by varying angles θ. As a result, grooves 1476 a-1476 f are lesslikely to contact belt 980 at the same point on belt 980 during rotationof pulley plate 1470. Thus, similar to pulley plates 1070, 1170, 1270and 1370, pulley plate 1470 provides maximum cleaning effort byproviding multiple belt-wiping grooves while minimizing wear upon belt980 by such multiple grooves.

Although illustrated as terminating prior to reaching center 1080, eachof grooves 1076, 1176, 1276 and 1376 may extend completely fromperimeter 1074 to center 1080. Similarly, grooves 1476 may alternativelyextend completely from perimeter 1047 to center of rotational axis 1076.Moreover, in lieu of extending completely to perimeter 1074, each ofgrooves 1076, 1176, 1276, 1376 may alternatively extend only partiallybetween perimeter 1074 and center 1080 so long as grooves 1076, 1176,1276 and 1376 have a length between center 1080 and perimeter 1074sufficient so as to insure contact with belt 980. Similarly, grooves1476 operatively extend only partially between perimeter 1074 and center1076 so long as grooves 1476 have a length between center 1076 andperimeter 1074 sufficient so as to insure contact with belt 980.Although grooves 1076, 1176, 1276, 1376, and 1476 are illustrated ascomprising linearly extending grooves or spirally extending grooves,such grooves may alternatively extend to any of a variety of shapes orconfigurations so long as the plurality of grooves collectively form apattern centered about a center offset from the rotational axis of thepulley plate or are unequally circumferentially spaced from one anotherby different angles. For example, in lieu of a linear or arcuate, eachof the subject grooves may be wavy, zigzagged or the like. Moreover, thesingle inner surface 1072 may include a plurality of differently shapedgrooves. For example, a single inner surface 1072 may include bothlinear and spirally extending grooves which are collectively centeredabout a center offset from the rotational axis of the pulley or whichare unequally circumferentially spaced from one another.

The pulley plate with belt wiping surface substantially improves thepower transmission effected by a torque sensitive pulley. A pulleyincorporating the pulley plate with belt wiping surface, as describedabove and in all its embodiments, is self-cleaning and thereforeimproves the frictional engagement between the belt and the pulleyplate. Thus, a pulley plate with a belt wiping surface increases theefficiency above that of a pulley without a belt wiping surface in itspulley plates.

The description above illustrates the use of the pulley plate with wipergroove in a harvesting machine. The pulley plate is also useful inconstruction and snowmobile equipment or equipment used in anenvironment where impurities are likely to be deposited on the pulleyplate or belt because the belt wiping surface cleans the impurities offof the belt. The belt-wiping surface increases the friction between thepulley plates and belt and thus is equally important in variable speedpulleys, even in clean environments, because the surface area ofengagement between the belt and the pulley plates is small and thefrictional engagement between the two is therefore vital to theefficiency of the pulley.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, although different preferredembodiments may have been described as including one or more featuresproviding one or more benefits, it is contemplated that the describedfeatures may be interchanged with one another or alternatively becombined with one another in the described preferred embodiments or inother alternative embodiments. Because the technology of the presentinvention is relatively complex, not all changes in the technology areforeseeable. The present invention described with reference to thepreferred embodiments and set forth in the following claims ismanifestly intended to be as broad as possible. For example, unlessspecifically otherwise noted, the claims reciting a single particularelement also encompass a plurality of such particular elements.

What is claimed is:
 1. A pulley plate for use with an opposing pulleyplate, wherein the plates receive a belt therebetween, the pulley platecomprising: an inner surface having an outer perimeter and a firstcenter about which the pulley plate is adapted to rotate; and aplurality of belt-wiping grooves in the inner surface at least partiallybetween the first center and the perimeter, the plurality of belt-wipinggrooves being unequally circumferentially spaced from one another abouta second center offset from the first center.
 2. The pulley plate ofclaim 1, wherein the plurality of belt-wiping grooves arcuately extendat least partially between the second center and the perimeter.
 3. Apulley plate for use with a belt, the pulley comprising: a firstsurface; a second surface facing the first surface, wherein the firstand second surfaces are spaced to receive the belt and adapted to rotateabout an axis extending through the first and second surfaces andwherein each of the first and second surfaces includes an outerperimeter; and a first plurality of belt-wiping grooves in the firstsurface at least partially between the axis and the perimeter, the firstplurality of belt-wiping grooves being unequally circumferentiallyspaced from one another about a center offset from the axis.
 4. Thepulley of claim 3 including a second plurality of belt-wiping grooves inthe second surface between the axis and the perimeter, the secondplurality of belt-wiping grooves being unequally circumferentiallyspaced from one another.
 5. The pulley of claim 3, wherein the firstplurality of belt-wiping grooves extend from the perimeter.
 6. Thepulley of claim 3, wherein the first plurality of belt-wiping grooveslinearly extend at least partially between the axis and the perimeter.7. The pulley of claim 3, wherein the first plurality of belt-wipinggrooves arcuately extend at least partially between the axis and theperimeter.
 8. A belt drive system comprising: a drive pulley including:a first inner surface; a second inner surface facing the first innersurface, wherein the first and second inner surfaces are spaced to forma first recess, wherein the first and second inner surfaces rotate abouta first axis extending through the first and second inner surfaces; adriven pulley including: a third inner surface; a fourth inner surfacefacing the third inner surface, wherein the third and fourth innersurfaces are spaced to form a second recess and wherein the third andfourth inner surfaces rotate about a second axis extending through thethird and fourth inner surfaces; and a belt received within the firstand second recesses to connect the drive pulley to the driven pulley,wherein at least one of the opposing inner surfaces includes a perimeterand a plurality of belt-wiping grooves unequally circumferentiallyspaced from one another and about a center offset from one of the firstand second axes.
 9. The system of claim 8, wherein the plurality ofbelt-wiping grooves extend from one of the first axis and the secondaxis to a perimeter of said at least one of the opposing inner surfaces.10. The system of claim 8, wherein the plurality of belt-wiping grooveslinearly extend at least partially between one of the first and secondaxes and the perimeter.
 11. The system of claim 8, wherein the pluralityof belt-wiping grooves arcuately extend at least partially between oneof the first and second axes and the perimeter.
 12. A pulley for usewith a belt, the pulley comprising: a first surface; a second surfacefacing the first surface, when the first and second surfaces are spacedto receive the belt, wherein the first and second surfaces are adaptedto rotate about an axis extending through the first and second surfacesand wherein each of the first and second surfaces include an outerperimeter; a first plurality of belt-wiping grooves between the firstsurface between the axis and the perimeter, the first plurality ofbelt-wiping grooves being centered about a first center offset from theaxis; and a second plurality of belt-wiping grooves in the secondsurface between the axis and the perimeter, the second plurality ofbelt-wiping grooves being centered about a second center offset from theaxis.
 13. The pulley of claim 12, wherein the first plurality ofbelt-wiping grooves linearly extend at least partially between the axisand the perimeter.
 14. The pulley of claim 12, wherein the firstplurality of belt-wiping grooves arcuately extend at least partiallybetween the axis and the perimeter.
 15. The pulley of claim 12, whereinthe first plurality of belt-wiping grooves are unequallycircumferentially spaced from one another.
 16. The pulley of claim 12,wherein the first plurality of belt-wiping grooves are equallycircumferentially spaced from one another.